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Guide to Electronic Testing--Table of Contents / Introduction



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Contents/Introduction (this page)

1. Test equipment

  • Multimeters
  • Adapters for multimeters
  • Oscilloscopes
  • Signal generators
  • Signal tracers
  • Capacitance meters
  • Frequency counters
  • Servicing test equipment

2. DC voltage tests and power supplies

  • DC voltage measurements
  • Problems with circuit breakers
  • Checking for a hot chassis
  • All-polarity voltmeters
  • Polarity indicators
  • Full-wave power supplies
  • Measuring ac voltages
  • Power supply ripple
  • Shortened power transformers
  • Power supplies with voltage dividers
  • Power supplies with dropping resistors
  • Power-supply circuits with branches
  • Transformerless power supplies
  • Half-wave voltage doublers
  • Full-wave voltage doublers
  • Full-wave bridge rectifiers
  • Electrolytic capacitors in series for higher working voltage
  • AC power supplies for transistorized equipment
  • Power supplies from a transformer winding on a phono motor
  • Transistorized capacitance multipliers
  • Checking capacitance multiplier circuits
  • Transistorized series voltage regulators
  • Transistorized shunt voltage regulators
  • Three-transistor voltage regulators for transistor TV sets
  • Transistorized dc-to-dc converters
  • Testing dc-to-dc converters
  • IC voltage regulators
  • Reading battery voltages correctly

3. Current tests

  • Power measurements
  • Measuring the dc drain of an auto radio
  • Dc current measurements in transistor portable radios
  • Testing power transformers for internal shorts
  • Substitute power testers
  • Finding overloads in power supplies
  • Selecting the bias of a power transistor with a current meter
  • Measuring large currents

4. VOM and VTVM tests

  • Measuring contact resistance with a VOM
  • Measuring voltage drop in long battery wires
  • Identifying uncoded wires in multiconductor cables
  • Testing capacitor leakage with a VTVM (vacuum tube volt meter)
  • Measuring very high resistances
  • Checking diodes by the balance method
  • Checking video-detector diodes with an ohmmeter
  • Checking video-detector diodes in-circuit with an ohmmeter
  • Checking transistors with a VOM
  • Voltage and resistance tests
  • Stacked stages
  • Bad base bias
  • Dealing with noise pick-up

5. Oscilloscope tests ( coming soon)

  • Calibration for direct measurements
  • Oscilloscope probes
  • Triggered and gated sweep
  • Measuring dc voltages with an oscilloscope
  • Measuring ac voltages with an oscilloscope
  • Measuring frequency with an oscilloscope
  • Analyzing distortion with an oscilloscope
  • Square-wave testing
  • Time and phase measurements
  • Using a sweep-frequency signal generator
  • Lissajous figures
  • Reactance and impedance measurements
  • Testing for filter ripple with the scope
  • Checking CB transmitter modulation with the scope

6. Component tests

  • Detecting thermal drift in resistors
  • Checking and repairing potentiometers
  • Capacitance testing
  • Testing variable capacitors
  • Testing inductors
  • Measuring inductance
  • Shorted power transformers
  • Testing integrated circuits, modules, and PC units
  • A quick check for microphones
  • Checking phone cartridges with the scope
  • Impedance checker for speakers
  • Testing diodes
  • Replacing transistors
  • Derating components

7. TV tests (i.e., classic television circuits -- this section may be added if we receive enough requests)

  • Measuring very high voltages
  • Measuring focus voltages in color TV
  • Checking color picture tubes with a VOM
  • Extension cables for testing TV tuners
  • A quick tuner gain check
  • Checking for operation of the 3.58 MHz color oscillator
  • Testing for presence of high voltage, horizontal sweep, etc.
  • Checking for high voltage with a neon tester
  • Setting a horizontal oscillator on frequency by comparing with video
  • Testing frequency in vertical-oscillator circuits
  • Finding the cause of sync clipping with the scope
  • Finding sync troubles with the scope
  • TV signal tracing and gain checks with an RF or AF signal generator
  • Signal tracing with the scope and color-bar patterns
  • Using the scope to set the duty cycle of the horizontal output transistor
  • How not to read voltages: The “do not measure” points in TV
  • Blown audio output transistors
  • Dealing with dead sets

8. Special tests

  • Measuring peak voltages without a voltmeter
  • Using a pilot lamp for current testing
  • A voltage divider for obtaining very small audio signals
  • A quick test for audio power output
  • Measuring amplifier output power with a multimeter
  • Testing an audio amplifier’s frequency response
  • A quick test for the RF power output of a transmitter
  • Measuring base bias voltage in high-resistance circuits
  • Finding breaks in multi-conductor cables
  • Finding a break in a coaxial cable with a capacitance tester
  • Measuring true rms voltages
  • Testing transistors
  • Testing Zener diodes
  • Testing FETS
  • Testing SCRs
  • Testing ICs

9. Signal tracing and alignment tests

  • Checking the calibration of an RF signal generator
  • Setting an RF signal generator on a crystal frequency
  • Finding the exact point of a zero beat
  • Test records: Good substitutes for the audio-signal generator
  • Using radio signals for testing stereo or PA systems
  • Using a communications receiver as an RF signal locator or tracer
  • The ac voltmeter for gain checks and signal tracing
  • Power output tests for PA and hi-fl amplifiers

10. Digital circuits ( coming soon)

  • Logic probes
  • Monitoring brief digital signals
  • Signal tracing in a digital circuit
  • Digital signal shape
  • Power-supply problems in digital circuits
  • Logic analyzers
  • Pulse generators
  • Flip-flops
  • Tri-state logic
  • Sequencing problems
  • Noise and glitches

11. Flowcharting and troubleshooting ( coming soon)

  • Basic flowchart
  • Servicing without a schematic
  • Systems comprised of multiple pieces of interconnected equipment

( coming soon)


INTRO

Electronics encompasses those things we can neither hear, see, touch, or taste. Electrical voltage, current, and resistance are in visible to the senses. Of course, you can directly sense an electrical shock, but to learn what’s going on within an electronic circuit, you must use test equipment. Test equipment is special apparatus designed to give visible or audible indications of what is there and what it’s doing.

Modern test instruments are amazingly versatile. They can do almost anything, if you know how to use them, how they work, and what their limitations are. If you don’t know how to use test equipment properly, it’s virtually useless. It’s also just as important to know what a test instrument can’t do. All test instruments can make the tests for which they are designed. Most can make many other tests as well, if you know how the instruments work and how their readings can indicate the presence or absence of other electrical parameters.

That’s what this guide is about—electronic tests and measurements, how to make them with all types of electronic test equipment, and how to interpret the results. Interpretation is the most important part of the whole process. It requires a full knowledge of both the test equipment and the circuits in which we’re taking the readings.

Electronics is a rapidly growing field, with new developments appearing almost daily. Although the basic principles of electronics theory remain the same, often new technology calls for new test procedures. In this Guide, every attempt has been made to provide as much up-to-date information as possible. Now-obsolete test procedures involving tube circuits were featured heavily in the original edition. This no-longer-relevant material has been eliminated and replaced with expanded information on testing transistor, and especially IC-based, circuitry.

The most important types of electronic test equipment are introduced in section 1. The following two sections cover a wide variety of voltage and current tests, some of which are less than obvious.

The two most widely used test instruments are the multi- meter (VOM, VTVM, or DMM) and the oscilloscope. Basic and advanced test procedures using these powerful test instruments are covered in sections 4 and 5.

At some point in servicing an electronic circuit, you will need to determine whether or not a specific component has gone bad. Section 6 offers many tips on testing various specific types of electronic components.

A number of test procedures for television circuits are given in section 7. Section 8 features a number of more or less unclassifiable special test procedures, including tests for various types of semiconductors. Section 9 covers signal tracing and alignment tests.

Section 10, on digital circuits, has been significantly expanded in this edition in response to the growing emphasis on dig ital circuitry in modern commercial equipment of all types.

Finally, section 11 covers the important principles of flow- charting and troubleshooting complex systems comprised of multiple circuits. This information will help you pinpoint the problematic stage, saving a lot of time that could be wasted in making unnecessary tests. Devoting a little time to thinking about the circuit before you turn on your test equipment will never be wasted time. In fact, in the long run, most servicing jobs will go much faster.

As you will discover as you go through this guide, there are many shortcuts — combinations of instruments and so forth — that you can use to test almost any electrical quantity, even those that might not appear to be within the range of your test equipment. A surprising number of electronic tests can be made with little more than a pilot lamp, a neon lamp, or a dc voltmeter. How ever, other tests require more sophisticated, arid expensive, equipment.

Although it’s obviously impossible for any single volume to cover every possible type of electronic test procedure, our goal has been to offer as wide a range of generally applicable procedures as possible. In updating the material for this guide, we have tried to live up to the title as much as possible and help the reader learn “how to test almost everything electronic.”


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Updated: Wednesday, 2014-07-02 17:24 PST